Human GHRH (Growth Hormone-Releasing Hormone) is a 44-amino-acid peptide whose full biological activity resides in its first 29 amino acids (“GHRH 1-29”). GHRH binds to the GHRH receptor and stimulates pulsatile GH [Growth Hormone] secretion, and with this mechanism of action GHRH represents an alternative to GH therapy in patients with an intact pituitary that may minimize the side effects associated with long-term GH administration. Because the quantity of GH release induced by GHRH is limited by IGF-1 levels, which exert a negative feedback effect, the risk of side effects associated with excessive GH secretion may also be lower with GHRH therapy than with GH therapy. In addition, treatment with GHRH may result in the pituitary secretion of a broader set of GH proteins, and not just the 22-kDa form provided by recombinant human GH, which may also have beneficial effects. Clinically, GHRH has been shown to be safe and effective in increasing GH levels in adults and children, and the growth-promoting effect of GHRH is correlated with the dose and frequency of administration. However, the half-life of GHRH after intravenous injection is only 10-12 min, which has significantly limited its use as a therapeutic agent. Thus there is a clinical need for analogs of GHRH that possess extended half-life in vivo that could provide greater therapeutic benefit with an improved (less frequent) dosing regimen.